The present invention pertains generally to electronic device enclosures and specifically to an electronic device enclosure having an integrated in-mold foil, which prevents fluid ingress around an included touch screen interface of the electronic device.
A resistive-type touch screen is a sensor consisting of two opposing layers, typically a flexible top layer and a supported bottom layer, each coated with a transparent resistive material called indium tin oxide (ITO). A pattern of very small transparent insulating dots separates the two opposing layers. When a finger or stylus touches the upper surface of the touch screen, electrical contact of the two layers between the span of insulating dots occurs. As the two ITO surfaces mate, the resistance of an electrical load across the screen changes, thereby indicating an output X-Y location of where the screen was touched.
Due to the sensitivity of the touch screen to pressure, there are problems associated with using a rubber gasket which surrounds the touch screen upper surface to prevent fluid ingress into the electronic device reliably. For example, for some use settings, applying the pressure to the gasket that is necessary to keep various chemicals and fluids from seeping in around the touch screen to the interior of the electronic device typically exceeds the sensitivity of the touch screen. As such, the touch screen in the vicinity around the gasket will register continually a touch, thereby making the touch screen unresponsive. Furthermore, using a gasket does not protect the upper surface of the touch screen from the environment. In some use settings, exposing the touch screen to various chemicals can cause damage (e.g., pitting, fading, weakening, hardening) to the flexible top layer.
A similar issue exists for the button(s) on a meter, where a button that deflects will open a hole through the housing, thus allowing a liquid breach. This can be problematic in some use settings, such as a hospital. As hospital meters are cleaned with corrosive fluid cleaners (e.g., bleach) daily, preventing fluid ingress and protecting the internal electronics and the touch screen from exposure to such cleaners is imperative for robustness.